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Microstructure and Texture Evolution During the Direct Extrusion and Bending–Shear Deformation of AZ31 Magnesium Alloy

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Acta Metallurgica Sinica(English Letters) 2019年第6期32卷 710-718页

作者： Xiao-Ye Liu Li-Wei Lu kun sheng Tao Zhou Hunan Provincial Key Laboratory of High Efficiency and Precision Machining of Difficult-to-Cut Material Hunan University of Science and TechnologyXiangtan 411201China School of Materials Science and Engineering Central South UniversityChangsha 410083China School of Materials Science and Engineering Chongqing University of TechnologyChongqing 400054China

AZ31 alloys were extruded by direct extrusion and bending–shear deformation(DEBS).The microstructure characteristic and texture evolution of DEBSed AZ31 sheets were investigated by electron backscattered diffraction(EBSD).It is found that DEBS technique could effectively refine grains and weaken ***,we also investigate how twinning affects dynamic recrystallization during hot extrusion.{10–12}extension twins can offer nucleation sites and enough energy to trigger dynamic ***,the character of direct extrusion and bending–shear die can lead to the activation of non-basal slip system and further dramatically weaken the basal texture of the microstructure with many preactivated basal slip systems.

关键词： Magnesium alloys Extrusion Grain refinement Texture evolution

Crack behavior in Mg/Al alloy thin sheet during hot compound extrusion

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Journal of Magnesium and Alloys 2019年第4期7卷 717-724页

作者： kun sheng Liwei Lu Yao Xiang Min Ma Zhiqiang Wu Hunan Provincial Key laboratory of High Efficiency and Precision Machining of Difficult-to-Cut Material Hunan University of Science and TechnologyXiangtanHunan 411201PR China College of Materials Science and Engineering Hunan University of Science and TechnologyXiangtanHunan 411201PR China Hunan Provincial Overseas-wisdom Innovation Center of New Energy Vehicle in Industrial-Academic-Research Cooperation Hunan University of Science and TechnologyXiangtanHunan 411201PR China

A novel and effective method to co-extrude metallic alloys is described which named Direct Extrusion and Bending-Shear *** compound extrusion plates have cracked at 290℃ and 3 mm/*** to this phenomenon,a model was built to investigate the crack generation and development between the 6061 Al and AZ31 Mg alloy during the compound extrusion process by *** cracking behavior of the Mg/Al composite rod with a soft Mg AZ31 core and a hard Al 6061 sleeve were systematically studied to disclose the influence of microstructure on crack in the different *** simulation results show that the distribution of strain and velocity has significant differences due to the influence of dies structure and material properties at different locations in the same *** experimental results show that in the same conditions,there are differences in recrystallization and texture weakening of AZ31 Mg alloys and 6061 Al alloy,which are important factors for the formation of *** the Mg layer and the Al layer have a homogeneous microstructure in the region d.

关键词： AZ31 Mg alloy 6061 Al alloy Compound extrusion Crack EBSD

Laser Shock Processing of Metal Sheet and Welded Joints

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材料热处理学报 2004年第05B期25卷 1053-1055页

作者： ZOUShi-kun TANYong-sheng ZHANGXiao-bin LIUFang-jun BeijingAeronauticalManufacturingTechnologyResearchInstitute China

In order to study the application of laser shock processing(LSP) as a post weld treatment technology and a strengthening technology, a series experiments and analysis were taken in this paper. The hardness of the laser shock processed zone of Al-Li alloy was measured, and the microstructure and mechanical properties of the welded joints of the Ni-based superalloy GH30 and the Austenitic stainless steel !Crl8Ni9Ti were compared with those without LSP in this paper. The results showed that the size of strengthened zone was similar to that of laser spot and strengthened layer was about 1mm deep, and the high intense dislocations and twins produced in the shocked zone. Plastic strain also gained surface residual compress stress, which is benefit for the fatigue properties of welded zones. In this test , the surface hardness of welding zone of the superalloy GH30 improved obviously and tensile strength increased by 12%, but the improvement of fatigue life was not obvious; Martensite phase is formed in plasma welding !Crl8Ni9Ti, which reduced the effect of strain deformation martensite induced by laser shock processing, but the surface residual compress stress gained by laser shock processing can obviously improve the fatigue life of !Crl8Ni9Ti welded joints.

关键词：激光冲击焊接接头硬度残余应力老化性能金属板

Microstructure and Mechanical Properties of AZ31 Mg Alloy Fabricated by Pre-compression and Frustum Shearing Extrusion

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Acta Metallurgica Sinica(English Letters) 2019年第2期32卷 235-244页

作者： kun sheng Li-Wei Lu Yao Xiang Min Ma Zhong-Chang Wang Hunan Provincial Key Laboratory of High Efficiency and Precision Machining of Difficult-to-Cut Material Hunan University of Science and Technology College of Materials Science and Engineering Hunan University of Science and Technology Department of Quantum Materials Science and Technology International Iberian Nanotechnology Laboratory(INL)

The AZ31 Mg alloys were processed by 6% pre-compression and frustum shearing extrusion at various temperatures, and the microstructure, texture and mechanical properties of the resulting alloys are systematically investigated. The results show that the grain size monotonically increases from 6.4 to 12.6 lm and the texture intensity increases from 6.7 to 9.6with the increase in the extrusion temperature. The combining effect of the pre-twinning and the frustum shearing deformation is found to contribute to the development of the weak basal texture in Mg alloys. The Mg alloy sheet produced at the extrusion temperature of 563 K exhibits excellent mechanical properties. The yield strength, ultimate tensile strength and elongation for the extruded alloys are 189.6 MPa, 288.4 MPa and 24.9%, respectively. Such improved mechanical properties are comparable or even superior to those of the alloys subjected to other deformation techniques, rendering the pre-compression and frustum shearing extrusion a promising way for further tailoring properties of Mg alloys.

关键词： AZ31 magnesium alloy Frustum shearing extrusion Microstructure Mechanical property Dynamic recrystallization

Energy Levels of Valence Subbands in Si/Si_(1-x)Ge_(x )Quantum Well byAdmittance Spectroscopy

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Chinese Physics Letters 2000年第4期17卷 288-290页

作者： LIN Feng GONG Da-Wei KE Lian ZHANG sheng-kun sheng Chi Surface Physics Laboratory Fudan UniversityShanghai 200433

Using the admittance spectroscopy technique,energy levels of subbands in SiGe/Si quantum well are *** value of activation energy increases with increasing well width,in accordance with the quantum confinement *** conductance peaks due to hole emission from heavy hole ground state and light hole ground state were *** was found that the value of activation energy increased with annealing time at the temperature of 800℃,while the activation energy decreases with the annealing time at 900℃.

关键词： effect. activation quantum

NUMERICAL MODELLING OF FREE-SURFACE FLOWS WITH BOTTOM AND SURFACE-LAYER PRESSURE TREATMENT

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Journal of Hydrodynamics 2009年第3期21卷 352-359页

作者： WANG kun State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China

A new non-hydrostatic numerical model with the three-dimensional Navier-Stokes equations on structured grids was constructed and discussed. The algorithm is based upon a staggered finite difference Crank-Nicholson scheme on a Cartesian grid. The eddy viscosity coefficient was calculated by the efficient k-ε turbulence model. A new surface-layer non-hydrostatic treatment and a local cell bottom treatment were introduced so that the three-dimensional model is fully non-hydrostatic and is free of any hydrostatic assumption. The developed model is second-order accuracy in both time and space when semi-implicit coefficient is set to 0.5. The validity of the present solution algorithm was demonstrated from its application to the three-dimension channel flow and the wave propagation over a submerged bar problems.

关键词： Navier-Stokes equations implicit k -ε turbulence model surface-layer non-hydrostatic treatment local cell bottom treatment

Do Cation-π Interactions Exist in Bacteriorhodopsin?

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Chinese Physics Letters 2001年第2期18卷 298-300页

作者： HU kun-sheng WANG Guang-Yu HE Jin-An Institute of Biophysics Chinese Academy of SciencesBeijing 100101

Metal ions are essential to the structure and physiological functions of *** evidence suggests the existence of specific cation binding to the negatively charged groups of Asp85 and Asp212 via an electrostatic ***,only using electrostatic force is not enough to explain the role of the metal cations because the carboxylate of Asp85 is well known to be protonated in the M *** the presence of some aromatic amino acid residues in the vicinity of the retinal pocket,the existence of cation-πinteractions between the metal cation and aromatic amino acid residues is ***,introduction of this kind of interaction is conducive to understanding the effects of the metal cations and aromatic amino acid residues inside the protein on the structural stability and proton pumping of bacteriorhodopsin.

关键词： interaction residues electrostatic

Shortening the manufacturing process of degradable magnesium alloy minitube for vascular stents by introducing cyclic extrusion compression

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Journal of Magnesium and Alloys 2024年第8期12卷 3204-3215页

作者： kun sheng Wenkai Li Peihua Du Di Mei Shijie Zhu Liguo Wang Shaokang Guan School of Materials Science and Engineering&Henan Key Laboratory of Advanced Magnesium Alloys Zhengzhou UniversityZhengzhou 450001China Key Laboratory of Advanced Materials Processing&Mold Ministry of Education Zhengzhou 450002China

Due to its excellent biocompatibility and biodegradability,Mg and its alloys are considered to be promising materials for manufacturing of vascular ***,the manufacture of high-precision and high-performance Mg alloys minitubes is still a worldwide problem with a long manufacturing processing caused by the poor workability of Mg *** solve this problem,the cyclic extrusion compression(CEC)was used to pretreat the billet by improving the workability of Mg alloys,finally shortening the manufacturing *** CEC treatment,the size of grains and second phase particles of Mg alloys were dramatically refined to 3.2μm and 0.3μm,*** after three passes of cold drawing,the wall thickness of minitube was reduced from 0.200 mm to 0.135 mm and a length was more than 1000 *** error of wall thickness was measured to be less than 0.01 mm,implying a high dimensional *** yield strength(YS),ultimate tensile strength(UTS)and elongation of finished minitube were 220±10 MPa,290±10 MPa and 22.0±0.5%,*** addition,annealing can improve mechanical property and corrosion resistance of minitubes by improving the homogeneity of the microstructure and enhancing the density of basal texture.

关键词： CEC ZE21B Mg alloy Minitube Shortened procedure Cold drawing Annealing

Preparation and Characterization of UV-absorbing PVDF Membranes via Pre-irradiation Induced Graft Polymerization

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Chinese Journal of Polymer Science 2019年第5期37卷 493-499页

作者： Li Dong Xiang-Dong Liu Zheng-Rong Xiong De-kun sheng Yan Zhou Yu-Ming Yang Changchun Institute of Applied Chemistry Chinese Academy of Sciences University of Science and Technology of China

Herein, excellent UV-absorbing poly(vinylidene fluoride)(PVDF) membranes were fabricated through the pre-irradiation induced graft polymerization method. The PVDF chains irradiated with ^(60)Co γ-ray were modified with the polymerizable UV absorber 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2 H-benzotriazole(RUVA-93). The influences of irradiation dose and monomer concentration on the prepared PVDF-g-PRUVA-93 membranes were investigated, and the optimal condition was eventually obtained. The chemical structures of the films were studied by ~1H-NMR, FTIR, and XRD. UV light transmittance and DSC tests were used to characterize the UV-absorbing performance and thermal property of the PVDF films before and after modification. The results proved that the PRUVA-93 side chains were successfully incorporated into the PVDF main chains and the obtained PVDF-g-PRUVA-93 films possessed remarkable UV-absorbing property. The modified membrane made under the optimized experiment condition could completely block the UV light in the range of 200-387 nm. Additionally, the transmittance of the PVDF-g-PRUVA-93 film could be reduced to0.04% in 280-320 nm, where the light irradiation could damage polymer materials most seriously.

关键词： PVDF membrane Modification Irradiation Grafting UV-absorbing